Light emitting diodes (LEDs) have many useful commercial applications. Because they are monochromatic, LED lights have great power advantages over white lights especially in applications in which a specific color light is needed. Unlike the white lights, the LED does not need a color filter that absorbs most of the emitted white light. Since LED lights are inherently colored and are available in a wide range of colors, LEDs have become of choice in many lighting applications.
One application for LEDs is in opto isolation products, such as opto couplers. The assignee of the present patent application is a manufacture of such opto isolation products. Examples of these opto-isolation products are described at the following Internet address, www.agilent.com.
An opto-coupler includes both a photo detector and a light emitting diode that are separately manufactured on separate integrated circuit or die. Accordingly, one step in manufacturing opto-couplers is the combining of the photo detector IC and the LED IC. Currently, an isolation tape with epoxy on both sides thereof is utilized to attach the LED to the photo detector IC.
Unfortunately, this process for combining the photo detector IC and the LED IC suffers from several drawbacks or disadvantages. First, the application of the epoxy on the isolation tape has very tight process constraints. For example, any excessive epoxy flowing towards the wire bond pad increases the likelihood of difficulty in subsequent wire bonding processing steps. The application of the epoxy is further complicated by the very small amount of clear epoxy that needs to be dispensed.
Second, and perhaps more detrimental, the placement of the isolation tape is critical to the success of the product. For example, misalignment of the isolation tape can result in poor isolation. Third, the optical transmittance of the isolation tape reduces the coupling efficiency of the opto-coupler.
Based on the foregoing, there remains an opto-coupler and method for manufacturing the same that overcomes the disadvantages set forth previously.